Fisheries Organization

NOT TO BE CITED WITHOUT PRIORREFERENCE TO THE AUTHOR(S)

NAFO SCR Doc. 81/VI/26

SCIENTIFIC COUNCIL MEETING - JUNE 1981

orthwest Atlantic

Serial No. N305

Historical records of mature female short-finned squid (Illex illecebrosus)4from the Northwest Atlantic and the first record ofa mature female aptured inshore at Newfoundland

by

E. G. Dawe, and H. J. DrewFisheries and Oceans

Researcl and Resource ServicesNewfoundland Region1P. 0: Box 5667

St. ohn's, NewfoundlandA1C 5X1

Abstract

A mature female short-finn@d squid captured inshore on the west coast of

Newfoundland on September 26, 19180 represents the first reported capture this

far north of a female in such an advanced stage of maturity. Ova in the

oviducts were in various stages of development and were larger than those in

the ovary. Fecundity for this pecimen was comparable to previous estimates

for mature females from the wiTtil population.

Maturity stages were assigned to this female and similar specimens captured

previously by applying indices of maturity which were developed using data

from captive females. Stages 6 maturity corresponded to descriptions of

maturity based on visual examination. Distribution of captures of mature

females suggests that high temperatures may be associated with atypically

early maturation.

Introduction

Biological characteristics of short-finned squid (Illex illecebrosus)

have been well described for on y a portion of its life cycle. The biology of

the species has been documented for that period between their first yearly

occurrence on the continental shelf in May-June until their disappearance from

inshore areas and the continental shelf in Novomber. Recently, earlier stages

of the life history have been d i scribed during the February-April period in

the Northwest Atlantic (Amaratunga et al., MS 1980; Fedulov and Froerman, MS 1980).

Ova sizes were measured to the nearest 0.01 mm using an ocular micrometer

exact counts of three 100 mg samples of ova from the oviducts.estimated from

fitted to a Bausch and Lomb dissecting microscope. Mean size of ova from the

oviducts and ovary were calculated from measurements of. ova from each

Since ova , from the ovary were smaller and attached to ovary tissue,

an estimate of fecundity was obtained only for the oviducts. Fecundity was

pertaining to historical captures of mature females were taken from

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However, little data have been collected between December and February

which is believed to encompass such critical phases in the life cycle as final

maturation and spawning (Squires, 1967). The process of maturation in males

is better understood than for females since males reach advanced stages of

maturity during their summer-autumn residence in inshore waters and on the

continental shelf (Squires, 1957; Mercer, MS 1973). Sexual maturation in

females is as yet undescri bed from field data since very few mature females

have been captured (Squires, 1957; Mercer and Paulmier, MS 1974).

Recently female short-finned squid have been maintained in captivity and

have undergone complete maturation and spawning (Durward et al., 1979, 1980;

O'Dor et al., MS 1980). Observations of spawning, as well as embryonic and

early larvaldevelopment have been recorded and fecundity has been estimated.

Also, a scale of female maturity stages has been developed and an index of

matLe ity has been proposed for future use in field studies (Durward et al., 1979).

In this paper the capture of a mature female short-finned squid inshore

at Newfoundland is reported for the first time. Ova sizes and fecundity are

described and records of previous captures of females in advanced stages of

maturity are reviewed. The index of maturity based on the relationship of

nidamental gland length to mantle length is calculated for these specimens and

compared to corresponding values gained experimentally (Durward et al., 1979).

Materials and Methods

The mature female short-finned squid captured inshore, was part of frozen

commercial samples collected from the West Coast of Newfoundland (NATO Div. 4R).

It was captured September 26, using a Japanese mechanical jigger at Cox's Cove,

Bay of Islands (Fig. 1). Examination and all measurements were later performed

on the specimens in thawed condition. Lengths were measured to the nearest

millimeter and weights were determined to thr nearPst 0.01 q.

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original detailed sampling sheetS and trip reports (Mercer, MS 1969 and unpubl.

material). These females were collected using bottom trawl during surveys

conducted by the Department of Fisheries and Oceans and the Institut Scientifique

et Technique des Peches Maritimes, Saint-Pierre and Miquelon. Vessels involved

were A.T. CAMERON (1968 and 1969), CYROS (1973) and NEWFOUNDLAND HAWK (1978).

Only speCimens which were positi llvely identified as Illex illecebrosus were

considered since, during several cruises extending into NAFO Subarea 6, catches

also included Illex oxygonius and Illex coindetii. Identification of specimens

captured during such cruises were performed by Dr. C. C. Lu.

Mantle length for these specimens was recorded to the nearest 0.5 cm,

whereas nidamental gland length was measured to the nearest millimeter. Data

were also available on ova diameter for the specimen captured in May, 1973

(Mercer and Paulmier, MS 1974). All measurements were performed on specimens.

.in fresh condition.

Results

The location of capture of a mature female short-finned squid on September 26, 1980

is shown in relation to historical captures of similar specimens (Fig. 1; Table 1).

Most earlier captures occurred further south. One specimen (August 19, 1969)

was captured in close proximity to the 1980 specimen, but it had not attained

such an advanced stage of maturity (Table 1). All but two of these specimens

were captured during August and all were in more advanced stages of maturation

than is normally observed in late autumn commercial samples. The May 1973

specimen and two of the three females captured during August 1968 in NAFO

Subarea 6 had mated (Table 1), 'as indicated by the presence of spermatophores

inside the mantle cavity.

The September 26, 1980 specimen was described as mature based on visual

examination (Fig. 2), the nidamental glands were greatly enlarged, white and

firm. The oviducal glands were swollen and the oviducts and ovary were yellow

and also enlarged. Ova were loose in the mantle cavity upon dissection.

Oblate spherical ova in tIe oviducts ranged in size from 0.76 x 0.69 mm

to 1.63 x 1.09 mm. The average size for the sample was 0.88 x 0.75 mm. Those

examined from the ovary were much smaller ranging 0.29 x 0.22 mm to 0.69 x 0.30 mm

with a mean size of 0.38 x 0.26 mm.

The oviducts contained 19.27 g of ova in various stages of development.

An estimate of fecundity for this specimen was 36,288 ova. An index of maturity,

based on the relationship of ovary weight (52.16 g) to body weight (155.84 g)

was 0.34.

An index of maturity, based on the relationship of nidamental gland

length to mantle length was calculated for the 1980 specimen and other specimens

captured previously (Table 1). Values for this index ranged from 0.24 to

0.47. Based on this index the 1980 specimen and all three earlier specimens

which had mated corresponded to stage V of maturity. The other three specimens

corresponded to stage IV.

Discussion

The September 26, 1980 capture of a mature female short-finned squid

represents the first record of a female in such an advanced stage of maturity

from inshore Newfoundland waters. The fact that the only previous capture of

an P l rly-season maturing female this far north occurred in the same general

area suggests that higher temperatures in the vicinity of the Gulf of St. Lawrence

may be associated with acceleration of sexual maturation. Males from the West

Coast were found to be more mature than those from other areas of insular

Newfoundland (Beck et al., this meeting). Mercer (MS 1973) noted that areal

differences in the rate of maturation of males may be due to variations in

temperature. -

All captures of mature females in NAFO Subarea 6 occurred during late

August or early September. However such occasional captures probably do not

indicate time of spawning, as few surveys have been conducted in this area

later in the year. Durward et al. (1980) noted that such rare captures are

probably oddities, rather than a part of the normal breeding population.

The females captured between June and September seem to have matured

atypically early. However, the May 1973 specimen was probably one which

matured and mated the previous winter, but did not spawn. This is suggested

by the anomalously large size of the specimen and the high index of maturity,

based on the relationship of nidamental gland length to mantle length. The

mean size of ova for this specimen was 0.9 x 0.6 mm (Mercer and Paulmier, MS 1974),

larger than that for the September 1980 specimen, but the same size as for

females which matured in captivity (Durward et al., 1979). The capture of two

other mature females on the Grand Bank in May has been previously reported

(Squires 1957). These were large specimens with ova diameters of 0.83 mm and

1.00 mm, indicating that they had also probably matured the previous winter.

An estimate of fecundity for the 1980 Newfoundland specimen (36,288) was

much lower than that estimated for captive females (400,000) (Durward et al., 1979)..

However it closely approximates estimates obtained by Lipinski (MS 1979) for

two maturing specimens captured in late May, 1975 in NAFO Subarea 6. Using a

similar method Lipinski estimated fecundity to be 31,100 and 39,400 for these

specimens which were smaller than the 1980 specimen described here. Although

fecundity for the 1980 specimen may be an underestimate, since freezing may

have caused some of the ova to rupture (O'Dor, pers. comm.), close agreement

with estimates of Lipinski suggest that actual fecundity may be much lower

than estimated from captive females (Durward et al., 1979). Fecundity of1

Illex illecebrosus is probably related to the number of finished ova in the

oviducts at time of spawning (0 1 por et al., MS 1980) and may further be reduced

in that this species does not appear to be a complete spawner (Durward et al., 1980).

Large uniform ova sizes and high estimates of fecundity for captive females

probably reflect atypically complete maturation of these females in the absence

of males. The presence of mature males is believed to serve as the spawning

stimulus (O'Dor et al., MS 1980);.

Classification of the 1980 specimen as stage V based on the OW and NGL ratiosBW ML

agrees with the subjective classification based on visual examination. Also, using

the NGL index all three mated females captured earlier were classified as stage V.ML

Thus, although unavailability of data throughout the continuous process of

maturation has precluded exact definition of maturity stages, the index of

maturity proposed by Durward et al. (1979) does appear to be applicable to

specimens from the wild population.

Acknowledgments

The authors acknowledge Mr H M. C. Mercer and Mr. G. V. Hurley under whose

supervision mature females were ,,'captured in various years. Thanks are extended

to Mr. P. W. Collins, Mr. W. R. Squires, and Mr. P. C. Beck who participated

in cruises and collected historical data presented here. Identification of

specimens by Dr. C. C. Lu is appreciated. Thanks are also extended to M r

H.. Mullett and Mr. G. King for preparation of figures.

References

Amaratunga, T., T. Rowell, and M. Roberge. MS 1980. Summary of joint Canada/USSR

research program on short-finned squid (Illex illecebrosus) 16 February

to 4 June 1979: spawning stock and larval survey. NAFO SCR Doc. 80/11/38,

Ser. No. N069, 36 p.

Durward, R. D. T. Amaratunga, and R. K. O'Dor. 1979. Maturation index and

fecundity for female squid, Illex illecebrosus (LeSueur, 1821). ICNAF

Res. Bull 14: 67-72.

Durward, R. D., E. Vessey, R. K. O'Dor, and T. Amaratunga. 1980. Reproduction

in the squid, Illex illecebrosus: first observations in captivity and

implications for the life cycle. ICNAF Sel. Pap. 6: 7-13.

Fedulov, P. P and Yu. M. Froerman. MS 1980. Effect of abiotic factors on

distribution of young shortfin squids, Illex illecebrosus (LeSueur, 1821).

NAFO SCR Doc. 80/VI/98, Ser. N . N153, 22 p.

LipiH,ki, M. MS 1979. Universal maturity scale for the commercially-important

squids (Cephalopoda: Teuthoidea). The results of maturity classification

of the Illex illecebrosus (LeSueur, 1821) populations for the years

1973-1977. ICNAF Res. Doc. 79/11/38, Ser. No. 5364, 40 p.

Mercer, M. C. MS 1969. A. T. CAMERON cruise 150, otter-trawl survey of the

mid-Atlantic Bight, August-September 1968. Fish. Res. Board Can. Tech.

Rep. No 122, 47 p.

MS 1973. Sexual maturity and sex ratios of the ommastrephid squid,

Illex illecebrosus (LeSueur), at Newfoundland (Subarea 3). ICNAF Res.

Doc. 73/71, Ser. No. 3023, 14 p.

Mercer, M. C., and G. Paulmier. MS 1974. Distribution and biological characteristics

f the short-finned squid (Illex illecebrosus) on the continental shelf

of subareas 3 and 4 in May-June, 1973. ICNAF Res. Doc. 74/87, Ser.

No 3323, 11 p.

O'D r, R. K. E. Vessey, and T. Amaratunga. MS 1980. Factors affecting

fecundity and larval distribution in the squid, Illex illecebrosus. NAFO

SCR Doc. 80/11/39, Ser. No. N070, 9 p.

Squires, H. J. 1957. Squid, Illex illecebrosus (LeSueur), in the Newfoundland

fishing area. J. Fish. Res. Board Can. 14: 693-728.

1967. Growth and hypothetical age of the. Newfoundland bait squid

Illex illecebrosus illecebrosus. J. Fish. Res. Board Can. 24: 1209-1217.

Time of capture Location of Mantle • Nidamental gland NGL Stage ofYear Date capture length (mm) length (mm) ML Maturitya

Table 1. Time and location of historical captures of female short-finnedsquid in advanced stages of maturity. Maturity stages are assigned basedon NGL relationship. (An asterisk indicates females which had mated).

ML

1980 Sept. 26

1978 June

1973 May 12

1969 Aug. 13

1968 Sept. 6

1968 Aug. 28

1968 Aug. 28

Bay of Islands 244

44055130"N55°40 1 00N 235

42°24 1 80"N 30564°52'40"W

48°14'00N 20559045130"14

39°00 1 00"N 25572°48100N

38°33'00"N 23573°17'15N

36°30 1 30"N 26076°29'00"W

115 0.47

77 0.33 IV

132 0.43 V

63 0.31 IV

105 0.41

89 0.38

62 0.24 IV

as proposed by Durward et a . (1979).

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Fig. 2. Mature female short-finned squid captured September 26, 1980 atCox's Cove, Bay of Islarlds, Newfoundland (ng = nidamental gland;od = oviduct; og = ovidUcal gland; o = ovary).

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